(a) A well known embodiment of the vehicle measuring instrument of this type as shown in FIG. 1.
There are provided a pair of longitudinally extending frames 1 across which a necessary number of transverse frames 2 extend. Each of the transverse frames 2 is provided on its lower side adjacent opposite ends with sliders 3, one for each end, by which this transverse frame 2 is slidably movable along the longitudinal frames 1. The longitudinal frames 1 and the transverse frames 2 respectively have measuring scales (not shown) and constitute together a base frame 4. Each of the longitudinal frames 1 carries on its upper side a pair of suspenders 6 each provided at its lower end with a slider 5 by which the associated suspender 6 is slidably movable along the associated longitudinal frame 1. Said suspenders 6 vertically extend and are held perpendicularly to the respective longitudinal frames 1. There are provided two holding rods 7 adapted to connect the respective lateral pairs of the suspenders 6 at their upper ends and each of such holding rods 7 is provided with a pair of connectors 8 being laterally slidable along holding rod 7 and mounted via holding rods 7 on associated suspenders 6. The connectors 8 are adapted to be connected to respective vehicle reference points 9a and the base frame 4 is suspended by the suspenders 6 from the vehicle 10.
One or two slider(s) 11 is or are slidably movable along each of the transverse frames 2 and has or have centrally on top surface(s) upwardly pointed pin(s) 13 having its or their upper end(s) defining reference portion(s) 12.
There are provided pendulum members 17 vertically extending and having upper ends as reference point corresponding portions 14 adapted to be connected to vehicle reference points 9b, and 9c, respectively, and lower ends defining pins 16 of which downwardly pointed ends 15 destined to be opposed to the associated reference portions 12. Each of the pendulum members 17 comprises a transparent pipe having a larger diameter and a measuring scale thereon and another pipe having a smaller diameter telescopically assembled so as to be extendible and contractible, and is vertically suspended from the vehicle reference point 9b or 9c under an effect of its own gravity, indicating a perpendicularity.
In such manner, possible deviations of the selected vehicle reference points 9b from their normal positions may be indicated (such arrangement is described in the specification of U.S. Pat. No. 4,329,784.).
(b) A well known manner in which the vehicle measuring instrument of this type has conventionally been used (see FIG. 1).
This has usually been accomplished by a sequence of operations (1) through (4) as follows:
(1) Operation of positioning the base frame and the arrangement associated with the vehicle reference points to be measured
Suitable two pairs of vehicle reference points 9a (i.e., four points) precisely lying in a laterally symmetric relationship are selected from the undersides of the right and left door sills of the vehicle 10, then a single vehicle reference point 9b to be determined of a position deviation is selected from the vehicle 10, the normal dimensional relationship of these vehicle reference points 9a and 9b not only in longitudinal but also in transverse directions is determined in reference with the plan view showing the vehicle dimensional schema, then four connectors 8 and one reference portion 12 are positioned on the base frame 4 according to the arrangement defined by said normal dimensional relationship. Now, the normal vertical dimensions of these vehicle reference points 9a and 9b with respect to the vehicle reference plane are respectively determined from the side view showing the vehicle dimensional schema, lengths of four suspenders 6 are adjusted to the vertical dimensions of said normally positioned four vehicle reference points 9a, respectively, and the length of the pendulum member 17 is adjusted to the vertical dimension of said single vehicle refernce point 9b to be measured. Then, the connectors 8 of the four respective suspenders 6 and the reference point corresponding portion 14 of said single pendulum member 17 are connected to the corresponding reference points 9a and 9b so as to suspend the base frame 4 and the single pendulum member 17 from the vehicle 10.
(2) Operation of detecting an error due to inclination of the vehicle
A necessary number (usually in order of four) of normally positioned vehicle reference points 9c are selected from the vehicle 10 and the correspondingly necessary number (usually in order of two) transverse frames 2 are provided across the longitudinal frames 1. The dimensional relationship of these normally positioned vehicle refernce points 9c not only in longitudinal but also in transverse directions is determined in reference with the plan view showing the vehicle dimensional schema to position four reference portions 12, two for each of these two transverse frames 2 in conformity with the respective vehicle reference points 9c. On the other hand, there are provided the same number of the pendulum members 17 as the number of these normally positioned vehicle reference points 9c and vertical dimensions of the respective vehicle reference points 9c with respect to the vehicle reference plane are determined in reference with the side view showing the vehicle dimensional schema so that lengths of the respective pendulum members 17 are adjusted to the vertical dimensions of the respective vehicle reference points 9c and said pendulum members 17 are suspended from the associated vehicle reference points 9c (with the vehicle measuring instrument of this type, it is preferred to select the vehicle reference points 9a, 9b, 9c lying in similar levels, if necessary, when these vehicle reference points 9a, 9b, 9c are selected, or to make the respective reference portions 12 level-adjustable on the base frame 4 so that the suspenders 6 and the pendulum members 17 may be adjusted to similar lengths, if necessary.). Even a slight inclination of the vehicle 10 during this adjustment (such an inclination of the vehicle 10 is almost inevitable, as will be described later) causes a perpendicularity indicated by each pendulum member 17 to deviate from the vertical direction of the vehicle 10. Thus, the opposing portions 15 of the respective pendulum members 17 suspended from the normally positioned vehicle reference points 9c deviate from the positions of the corresponding reference portions 12 in longitudinal, transverse or composite direction. Such deviations may be determined to detect the error due to the inclination of the vehicle 10.
It should be noted here that, if the vehicle 10 is accurately horizontal during this adjustment (such a situation is not absolutely impossible but rare), said opposing portions 15 will be in alignment with the corresponding reference portions 12 so that the operation 2 can be followed directly by the Operation of Measurement 4 as will be described in detail. However, the operation 2 is usually followed by an operation 3.
(3) Operation of compensating an error due to inclination of the vehicle
The operation of finely adjusting positions of the reference portions 12 in longitudinal direction by manually displacing the longitudinal frames 1 from a state in which said longitudinal frames are freely slidable with respect to the sliders 5 of the suspenders 6 and the operation of finely adjusting positions of the reference portions 12 in transverse direction by manually displacing the holding rods 7 from a state in which said holding rods 7 are freely slidable with respect to the connectors 8 are repeated with caution to maintain a correct relative position of said reference portions 12 so that the respective reference portions 12 are positioned precisely in alignment with the opposing portions 15 of the corresponding pendulum members 17 suspended from said normally positioned vehicle reference points 9c.
(4) Operation of measurement
Amount and direction by and in which the opposing portion 15 of the pendulum member 17 suspended from said vehicle reference point 9b to be measured deviates from the corresponding reference portion 12 may be determined by measuring amount and direction by and in which said vehicle reference point 9c deviates from its normal position.
It should be noted here that the above-mentioned sequence of operations (1) through (4) is not always performed exactly in this order and sometimes any one of these operations may be interrupted by any other operation.
The vehicle measuring instrument of this type including the components such as the pendulum members and the reference portions constructed in manners other than those as mentioned above is also well known (not shown).
There is provided a transverse frame carrying a laser oscillator adapted to be laterally movable and to generate a laser in a longitudinal direction at the rear-most position on the base frame while there are provided laser oscillators adapted to be longitudinally movable and to generate lasers in transverse direction at the left ends of the respective transverse frames. These laser oscillators define the reference portions. On the other hand, each pendulum member comprises a pipe having on its upper end a reference point corresponding portion adapted to be connected to the corresponding vehicle reference point and on its lower end a transparent plate so that this pendulum member may be perpendicularly suspended, under an effect of its own gravity, from the vehicle reference point. Really, said pipe comprises an outer pipe of a larger diameter and an inner pipe of a smaller diameter being slidable within said outer pipe so that this pipe assembly may be telescopically extendible and contractible. The transparent plate is centrally provided with a spot-like mark serving as the opposing portion.
Further another arrangement is also well known in which the suspenders, each comprising a pipe having on its upper end a connector adapted to be connected to the corresponding vehicle reference point, are mounted on the transverse frames of the base frame perpendicularly to said transverse frames (see the specification of U.S. Pat. No. 3,869,804).
(c) Advantages and disadvantages of the well known vehicle measuring instrument of this type (see FIG. 1.).
It is extremely convenient or advantageous for persons such as the car mechanics that, even when an external force is accidentally applied to the pendulum member 17 during repair and maintenance of a vehicle, pendulum member 17 readily escapes so as to avoid possible damage and, once this external force has been removed, said pendulum member 17 immediately restores its initial position, since each pendulum member 17 is perpendicularly suspended from the vehicle in the well known vehicle measuring instrument of this type.
However, such arrangement of the pendulum members 17 results in that even a slight inclination of the vehicle 10 causes a perpendicularity indicated by each pendulum member 17 to deviate from the vertical direction of the vehicle 10 and a direct measurement leads to an erroneous result. It is for this reason that the operation of detecting an error due to inclination of the vehicle as set forth in said paragraph (2) and the operation of compensating an error due to inclination of the vehicle as set forth in said paragraph (3) are performed. Furthermore, even slight changes in the direction and in the inclination angle of the vehicle 10 occurring before a vehicle measurement has been completed will require a repetition of the operation of compensating an error due to inclination of the vehicle as set forth in said paragraph (3).
Such operation of error compensation cannot be accomplished at one end the car mechanic must walk about here and there around the vehicle 10 and repeat fine adjustment many times until the error will have progressively been compensated. Thus, this has been an extremely troublesome, time-consuming operation.
Additionally, the vehicle intrinsically has a tendency to incline due to uneven flattening of components such as suspensions and tires. Moreover, the floor in the workshop for vehicle repair and maintenance is generally inclined more or less as for improvement of drainage or somewhat irregular, although such floor appears to be horizontal and smooth. Thus, the vehicle 10 placed directly or with interposition of a bench or like on such floor is necessarily inclined. Inclination direction or inclination angle of the vehicle 10 often varies during operation of repair and maintenance due to an enormous force in order of several tons applied to the vehicle 10.
Thus, it has been inevitable that the vehicle 10 to be measured is inclined or the direction or angle of such inclination changes before the measurement has been completed. With the well known vehicle measuring instrument of this type, therefore, for every time that such phenomenon occurs, it has been inconveniently required to repeat the operation of detecting an error due to inclination of the vehicle as set forth in said paragraph (2) and the operation of compensating an error due to inclination of the vehicle as set forth in said paragraph (3).